Emil g



(No Model.)

B. 0. O. KROGH.

THERMOSTAT.

No. 497,800. Patented May 23, 1893.

aw/ Mada co UNITED STATES PATENT OFFICE.

EMIL C. C. KROGII, OF MONMOUTH, ILLINOIS, ASSIGNOR OF ONE-HALF TO S. D.MCGOVERN AND THOS. B. MOGOVERN, OF SAME PLACE.

THERMOSTAT.

SPECIFICATION forming part of Letters Patent No. 497,800, dated May 23,1893.

Application filed January 11, 1893- Serial No. 458,047. (No model.)

T0 00% whom it may concern:

Be it known that I, EMIL O. O. KROGH, a citizen of the United States,residing at Monmouth, in the county of Warren and State of Illinois,have invented certain new and useful Improvements in Thermostats; and Ido declare the following to be a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which itappertains to make and use the same, reference being had to theaccompanying drawii'lgs, and to the letters of reference marked thereon,which form a part of this specification.

My invention relates to fire alarms of the class employing an electriccircuit to actuate the alarm, which circuit is normally open, but isclosed by the action of a thermostat actuated by a rise in thetemperature in the surrounding atmosphere due to the presence of a fire.

More especially my object is the improvement of the thermostat shown inmy patent, No. 488,611, issued December 27, 1892, whereby the same maybe employed as an ordinary push-button type of circuit closer as well asoperating as a thermostat circuit closer.

To this end, and others to appear, the invention consists in theconstruction and combination of parts hereinafter specified, and shownin the accompanying drawings, in which- Figure 1, is a perspective Viewof my device; Fig. 2,-a view partially in section and partly inelevation, and Fig. 3, a detail perspective view of the contactadjusting cam.

As in my patent referred to, I employ an alcohol filled drum or capsuleA, that constitutes one terminal of the electric circuit, an adjustablerod B constituting the other terminal, a spiral cam O to adjust saidrod, dial D and a pointer or indicator E.

The cam O is mounted on the inner end of a shaft F journaled in ahearing or sleevef that is supported by an open frame of four rods f,secured to two diametrically extending bars d, 61. Upon its outer endthe shaft F is provided with an enlargement or button g by which it maybe rotated, and also moved longitudinally inward, to carry the rod Binto contact with the capsule A and thus close the circuit. The hand orpointer E is carried by said shaft F. The rod I3 does not engage thecam, as in my patent referred to, but a second rod 17 is employed whichis connected to a lateral extension of the rod B. A coiled springencircling the rod 1) presses the same yieldingly against the cam. Thisarrangement of the rods enables me to have the capsule A and the dial Dconcentric, instead of eccentric, as is the case with my patenteddevice.

To prevent the rod 1) from passing out of contact with the spiral cam 0when the latter is rotated from its highest to its lowest surface, Iprovide a projection c to strike said pin and thus limit the rotation ofthe cam.

As the frequent use of the device as an ordinary call, might dis-arrangethe adjustment of the device to acertain temperatureflhave provided alock to prevent such derangement, consisting of a toothed wheel hmounted on the shaft F, and a pawl I to co-operate therewith. Said pawlis made quite wide, as shown, so as to always engage the wheel, whatevermay be the position to which it may be moved by the longitudinalmovements of the shaft. The pawl is held locked in engagement with theteeth of the wheel, by a collar i mounted on one of the rods f whichengages the side of the pawl. Said collar is normally held outward inengagement with the pawl by a coiled spring ienciroling one of therodsf'. To disengage the pawl from the wheel it is simply necessary topressthe collar inward against the tension of the spring until it is outof the path of outward swing of the pawl.

It will be seen that with the additions made to my patented device, Ihave materially increased its utility, and without in any degreedetracting from its uses as an automatic firealarm, as regards itsfunctions as a thermostat, it operates in exactly the same way as saidpatented device, and possesses the same advantages.

The operation of the device constructed as above described issubstantially as follows: Normally the capsule A is out of contact withthe contact 13, but when the temperature of the atmosphere, due to thepresence of a fire, rises sufficiently, the capsule A is expanded untilit contacts with the terminal B, thus completing the circuit andsounding an alarm,

ICC

as in my patent hereinbefore referred to. Should it be desired to soundan alarm for any reason when the temperature is not sufficiently high toexpand the capsule, the push button 9 is pushed inward, which brings thecontact B against the capsule and closes the circuit.

Having thus described my invention, What I claim to be new, and desireto secure by Letters Patent, is

1. In combination with the temperature actuating contact of athermostat, the longitudinally movable rod forming a contact,heldnormally away from the other, the adjusting cam, the longitudinallymovable shaft carrying said cam, and the locking device consisting ofthe toothed wheel, the pawl and the collar, to hold said shaft fromrotation when moved longitudinally, substantially as described.

2. In combination with a temperature actuating contact of a thermostat,the longitudinally movable contact rod held normally from the other, theadjusting cam, the longitudinally movable shaft carrying said cam, thetoothed wheel to hold said shaft from rotating, and the spring pressedcollar to engage said pawl.

3. In combination with the temperature actuating contact of athermostat, the longitudinally movable contact rod forced normally fromthe other, the eccentric rod engaging the cam, and a spring around saidrod, the adjusting spiral cam to move said rod and the stop tolimit-rotary movement of the cam, substantially as described.

In testimony whereof I affix my signature in presence of two Witnesses.

EMIL C. (J. KROGH. l/Vitnesses:

T. C. PATTERSON, T. B. McGovERN.

